1. Field of the Invention
The present invention relates to a fuel vapor recirculation device. More particularly, the present invention relates to a fuel vapor recirculation device for a vehicle that can recirculate fuel vapor that is exhausted from a canister back to the canister, and minimize discharging fuel vapor to the atmosphere.
2. Description of Related Art
In the automotive industry, there has been research on improvement of emissions. For minimizing hydrocarbons (HC) in evaporation gas of gasoline fuel, emissions from fuel evaporation have been reduced to under 0.5 g/day in some countries, and it will be further limited to under 0.054 g/day by law.
For adhering to that limitation, improvements in fuel tank materials and optimizing connection structures have been studied in order to minimize generation of fuel evaporation gas that permeate the fuel tank, and a fuel vapor recirculation device provided with a canister has also been used.
The canister contains an absorbent material such as activated carbon for absorbing the fuel vapor or fuel evaporation gas from the fuel tank or a float chamber and for preventing discharge of the fuel vapor or fuel evaporation gas to the atmosphere.
The absorbed fuel vapor can be transmitted to an engine for combustion through a pressure control solenoid valve, for example, a Purge Control Solenoid Valve (PCSV) that is controlled by an engine control unit (ECU).
That is, a conventional fuel vapor recirculation device 101, as shown in FIG. 6, includes a fuel tank 103, a canister 105, a pressure control solenoid valve 107, a Canister Close Valve (CCV) 109, and an assistance canister 111.
The canister 105 is connected with the fuel tank 103 through a vapor line 113, to the pressure control solenoid valve 107 through a purge line 115, and to the canister close valve 109 through a vent line 117.
The assistance canister 111 is disposed to the vent line 117 that connects the canister 105 and the canister close valve 109.
The fuel vapor or fuel evaporation gas from the fuel tank 103 are absorbed to the canister 105 through the vapor line 113 and transmitted to an engine through the purge line 115 that is open or closed by the pressure control solenoid valve 107 in accordance with operation of the ECU 119.
Further, when the fuel vapor in the canister 105 is saturated, the canister close valve 109 is opened by operation of the ECU 119 and the fuel vapor is transmitted and absorbed to the assistance canister 111 and then discharged to the atmosphere, so that discharged fuel vapor can be minimized.
However, when the size of a canister of the conventional fuel vapor recirculation device is increased for reducing exhausted fuel evaporation gas, an unpredictable phenomenon can occur due to resistance in the canister, and the fuel tank can be repeatedly constricted due to negative engine pressure such that optimally constructing a fuel vapor recirculation device is difficult.
Also, when the assistance canister is used, discharging fuel vapor can be minimized, but cost for manufacturing and weight of a fuel vapor recirculation device is increased and layout is complicated.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.